dehub/change_hash.go
mediocregopher 7c891bd5f2 Initial commit, can create master commit and verify previous master commits
message: Initial commit, can create master commit and verify previous master commits
change_hash: ADgeVBdfi1hA0TTDrBIkYHaQQYoxZaInZz1p/BAH35Ng
credentials:
- type: pgp_signature
  pub_key_id: 95C46FA6A41148AC
  body: iQIzBAABAgAdFiEEJ6tQKp6olvZKJ0lwlcRvpqQRSKwFAl5IbRgACgkQlcRvpqQRSKzWjg/+P0a3einWQ8wFUe05qXUbmMQ4K86Oa4I85pF6kubZlFy/UbcjiPnTPRMKAhmGZi4WCz1sW1F2al4qKvtq3nvn6+hZY8dj0SjPgGG2lkMMLEVy1hjsO7d9S9ZEfUv0cHOcvkphgVQk+InkegBXvFS45mwKQLDOiW5tPcTFDHTHBmC/nlCV/sKCrZEmQGU7KaELJKOf26LSY2zXe6fbVCa8njpIycYS7Wulu2OODcI5n6Ye2U6DvxN6MvuNvziyX7VMePS1xEdJYpltsNMhSkMMGLU7dovxbrhD617uwOsm1847YX9HTJ3Ixs+M0yobHmz8ob4OBcZx8r3AoiyDo+HNMmAZ96ue8pPHmI+2O9jEmbmbH61yq4crhUVAP8PncSTdq0tiYKj/zaSTJ8CT2W0uicX/3v9EtIFn0thqe/qZzHh6upixvpXDpNjZZ5SxiVm8MITnWzInQRbo9yvFsfgd7LqMGKZeGv5q5rgNTRM4fwGrJDuslwj8V2B4uw1ofPncL+LHmXArXWiewvvJFU2uRpfvsl+u4is2dl2SGVpe7ixm+a088gllOQCMRgLbuaN8dQ/eqdkfdxUg+SYQlx6vykrdJOSQrs9zaX/JuxnaNBTi/yLY1FqFXaXBGID6qX1cnPilw+J6vEZYt1MBtzXX+UEjHyVowIhMRsnts6Wq3Z8=
  account: mediocregopher
2020-02-15 15:13:50 -07:00

76 lines
1.6 KiB
Go

package dehub
import (
"crypto/sha256"
"encoding/binary"
"fmt"
"hash"
"sort"
"gopkg.in/src-d/go-git.v4/plumbing/object"
)
var (
defaultHashHelperAlgo = sha256.New
)
type hashHelper struct {
hash.Hash
varintBuf []byte
}
// if h is nil it then defaultHashHelperAlgo will be used
func newHashHelper(h hash.Hash) *hashHelper {
if h == nil {
h = defaultHashHelperAlgo()
}
s := &hashHelper{
Hash: h,
varintBuf: make([]byte, binary.MaxVarintLen64),
}
return s
}
func (s *hashHelper) writeUint(i uint64) {
n := binary.PutUvarint(s.varintBuf, i)
if _, err := s.Write(s.varintBuf[:n]); err != nil {
panic(fmt.Sprintf("error writing %x to sha256 sum: %v", s.varintBuf[:n], err))
}
}
func (s *hashHelper) writeStr(str string) {
s.writeUint(uint64(len(str)))
s.Write([]byte(str))
}
func (s *hashHelper) writeTreeDiff(from, to *object.Tree) {
filesChanged, err := calcDiff(from, to)
if err != nil {
panic(err.Error())
}
sort.Slice(filesChanged, func(i, j int) bool {
return filesChanged[i].path < filesChanged[j].path
})
s.writeUint(uint64(len(filesChanged)))
for _, fileChanged := range filesChanged {
s.writeStr(fileChanged.path)
s.Write(fileChanged.fromMode.Bytes())
s.Write(fileChanged.fromHash[:])
s.Write(fileChanged.toMode.Bytes())
s.Write(fileChanged.toHash[:])
}
}
var changeHashVersion = []byte{0}
// if h is nil it then defaultHashHelperAlgo will be used
func genChangeHash(h hash.Hash, msg string, from, to *object.Tree) []byte {
s := newHashHelper(h)
s.writeStr(msg)
s.writeTreeDiff(from, to)
return s.Sum(changeHashVersion)
}